1. Field of the Invention
The invention relates to a resistance heating device for flat objects such as mirrors.
2. Discussion of the Background
Mirror surfaces often steam up following showering or bathing which prevents the mirrors from fulfilling their function. In order to keep a mirror from steaming up it is known to heat the mirror surface from the rear with heating layers so that the surface does not steam up, even in high air humidity. However, these heating devices have been restricted in countries that impose high safety requirements. For mirror heaters, this may mean that the power-carrying elements, i.e., the heating elements, must be safeguarded by insulating layers which are separated from one another. For example, embedding a serpentine resistance heater between three insulating layers separated from one another on both sides leads to a comparatively thick construction, which in turn results in less efficient heating. The large overall height and the loss of efficiency have kept flat heating devices of this type from becoming widespread, particularly for mirrors.